In recent years, environmental problems have become more pressing globally. To cope with this, regulations of exhaust gas for vehicles have been tightened.
Vehicle industries have invested enormous capital to develop an exhaust system for removing harmful components included in exhaust gas and have conducted many studies for a method for reducing harmful gas and enhancing fuel consumption.
As one of the methods for reducing harmful gas, a post-processing apparatus for purifying exhaust gas, for example, a diesel particulate filter (DPF) for reducing particulate materials (PMs) and nitrogen oxide (NOx), a diesel oxidation catalyst (DOC), and a Selective Catalytic Reduction (SCR) have been used in the exhaust system.
The post-processing apparatus has used metal materials such as platinum and palladium as a catalyst. To activate the catalyst, the supplied exhaust gas needs to be maintained at a predetermined temperature or more.
However, the related art takes a long time to increase a catalyst temperature using the exhaust gas after the engine starts or requires a method of increasing temperature by injecting fuel into the post-processing apparatus, a method for increasing temperature using an electric heater, etc. However, these methods may deteriorate the fuel efficiency of a vehicle.
In particular, the related art may excessively discharge the exhaust gas including a large amount of harmful ingredients due to an activation time delay of the catalyst since heat is discharged to the outside while the high-temperature exhaust gas combusted in the engine passes through an exhaust port, an exhaust manifold, etc.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.